Substance P, vasoactive intestinal polypeptide, and gastrin catabolism in canine liver and kidney.

No reports have described the catabolic mechanism of substance P in vivo. We studied the effects of hepatic or renal transit on substance P, vasoactive intestinal polypeptide, and gastrin in anesthetized dogs. It was found that the liver plays a more important role in vasoactive intestinal polypeptide catabolism than the kidney and that the kidney is more important in gastrin catabolism than the liver. Substance P was more rapidly degraded than the other two peptides in both organs. The transrenal substance P loss measured by C-terminal antiserum differed from that measured by N-terminal antiserum, although there was no difference in the liver. This suggested that there were different patterns of cleavage of substance P between the liver and the kidney, and that its C terminal was degraded more strongly than its N terminal in the kidney.